MODELING THE EFFECT OF PREFERENTIAL HERBIVORY IN TROPICAL FORESTS 2014 PEI Summer Internship Emily Shuldiner.

MODELING THE EFFECT OF PREFERENTIAL HERBIVORY IN

TROPICAL FORESTS

2014 PEI Summer InternshipEmily Shuldiner

Suchana Costa (‘14) Thesis:“Herbivory Constaints on Symbiotic N2-fixers in Young Recovering Tropical Rainforest”

From “Herbivory Constraints on Symbiotic N2-fixers in Young Recovering Tropical Rainforest,” by Suchana Costa, 2014

Agua Salud: Mosaic. Retrieved from the Smithsonian Tropical Research Institute website, www.ctfs.si.edu/aguasalud/page/catchments/#forest

The big question: How does the observed herbivory pattern affect the

tropical carbon sink?•(A) Model the effect of the herbivory pattern identified by Costa at current CO2 levels.

•(B) Model the effect the herbivory pattern, assuming rising CO2 levels.

Medvigy et al. (2009), JGR BiogeosciencesModeling the N deficit: Ecosystem Demography model 2 (ED2)

What goes in:Meteorology, Deposition

What comes out:Number density of trees -- of a given size -- of a given plant functional type

The cast:

The newcomer:N-fixer

The originaltrio of ED2tropical trees(all non-fixers)

(disturbed)

Incorporating Herbivory into the Model

-From Suchana Costa’s 2014 senior thesis:-Nonfixers (PFT 2,3,4): 0.9% leaf removed / month-Fixers (PFT 30): 3.0% leaf removed / month

-Herbivory represented in model as increase in underlying yearly leaf turnover rate.

A: Effect of HerbivoryTwo Possibilities:

• (1) Disproportionate fixer herbivory Diminished fixer growth Fixers less able to compete with non-fixers

• Competitive advantage to non-fixers

• (2) Disproportionate fixer herbivory Diminished fixer growth Less available N in ecosystem Non-fixers face severe N limitation

• Competitive advantage to fixers

Hurting fixers hurts non-fixers

The importance of fixers

B: Effect of Elevated [CO2] on Effect of Herbivory

• (1) How does increased [CO2] affect fixer abundance?

• (2) How does increased [CO2] affect the relative impact of herbivory.

Rising [CO2]0 increases net AGB

Forest Composition

Solid line- No Herbivory Dotted line- Herbivory

% AGB Lost to Herbivory